1. Field of Invention
The present invention belongs to a side slope excavating supporting technology field of infrastructures of civil engineering, water conservancy, mining, municipality, etc., and particularly relates to a polymer grouting method for constructing vertical supporting system of excavating of foundation pit, side slope, municipal pipeline, etc.
2. Description of Related Arts
Since the founding of People's Republic of China, remarkable achievements have been made in infrastructure constructions of civil engineering, water conservancy, municipality, etc. In the process of using the underground space and exploiting the mineral resources, when facing the complex geological conditions, the measure of side slope supporting is usually required to be taken. Very often, affect of groundwater should also be considered. With the development of geotechnical engineering technology, machine, civil engineering materials, etc., the side slope supporting technology develops effectively. Supporting structure systems, such as soil nailing wall, composite soil nailing wall, underground continuous wall, row pile supporting and anchor pile supporting, correspondingly emerged. Meanwhile, in order to control the influence that the groundwater has on the side slope supporting and underground construction, the water-stopping curtain or the auxiliary water-lowering measure is also considered to be installed in the supporting system. Especially under the conditions of high underground water level and limited slope space, some groundwater treatment measures, such as water lowering and water stopping, are required to be taken in the foundation pit supporting. In contrast, taking the measure of water stopping can guarantee the safety of the surrounding buildings, structures and the underground pipeline better. Nowadays, the water stopping method in the side slope supporting system is embodied as technologies, such as cement mixing piles, high-pressure jet grouting pile, and TRD method. The above supporting technologies played important roles in practical projects, but they also have some technical shortages. For example, it is difficult to use the soil nailing wall under the condition of soft soil, unbonded loose sandy soil and rich underground water. In addition, when the soil nailing wall is used as a permanent structure, the problem of durability, such as corrosion, should be considered. The design of the composite soil nailing wall is mostly borrowed from the design of soil nailing wall, and the role of advance supporting and water-stopping curtain are not considered in the design and calculation of the composite soil nailing wall. For the underground continuous wall, sandy soil and mud dug out requires for the settlement equipment and the mechanical equipment, so the cost is high. In addition, the drainage tends to pollute the underground water, and excavating the slot tends to cause the settlement of the buildings. For the row pile supporting structure, there is no mature design method at present, and there are few systematic and in-depth researches on the stress mechanism, the working properties and the applicable conditions of the row pile. In addition, in the aspect of water-stopping material, the conventional side slope supporting technology mostly uses cement materials, so the water stopper constructed is a rigid solid having an elastic modulus greatly different from the elastic modulus of the soil, and is poor in impervious anti-cracking property. In the aspect of water-stopping mechanism, in the conventional technology, the materials and the soil are disassembled, when stopping the water, and the material grouted in is difficult to form a complete continuum. In the aspect of the construction, in the several conventional technologies, the water stopper is formed by the construction methods, such as excavating slots, mixing, spraying and vibrating, so the side slope structure is greatly damaged by turbulent motions. Thus, it is clear that these supporting technologies frequently used in projects mostly have shortages of great turbulence damages to the side slope, long construction period, high cost, inconvenient construction, etc. In addition, in some complicated stratum conditions, even if the different combination of the above various side slope supporting methods and water-stopping construction methods are applied, it is still difficult to meet the requirement of safety, practicality, economy, rationality, reliable quality, protecting environment, etc., so safety accidents caused by improper design and improper handling of construction occurs frequently. For the powder sands, the fine sand layer and the soil layer, which are relatively loose, if adopting the design idea of excavation and supporting at a same time, landslides tend to occur before the supporting structures are constructed in the excavation process. If the method of improved soil slope is adopted in advance, the construction period will be extended to 2˜3 times, and the cost will increase by more than 1 time. The current situation is not suitable for the development requirement of the infrastructure building of civil engineering, water conservancy, mining, municipality, etc. of our country at present. Therefore, the research and development of the supporting system combining supporting structure and the water-blocking function is an important technological problem to be solved in the present in the side slope excavation process of civil engineering, water conservancy and municipality infrastructure constructions, such as foundation pit, side slope and municipal pipeline excavation.
Polymer grouting technology is a rapid foundation reinforcement technology developing in the 1970s. This technology takes advantage of characteristic that the polymer materials expand rapidly and solidify after the chemical reaction to reinforce the foundation, fill the void, and raise the floor by injecting the polymer materials into the foundation. At present, the polymer grouting technology is mainly applied in field of foundation reinforcement of industrial and civil building and road maintenance. The present invention provides a polymer grouting method for constructing a vertical supporting system combining water-blocking function and supporting reinforce function, and provides a new supporting technology to excavation of foundation pit, side slope and municipal pipeline. At present, there is no report related to the polymer grouting method for constructing vertical supporting system.